... FUELBOT can't measure how much fuel has been entered ...
For the initial calibration, you need to get how much you filled off the pump's meter.
Pumps are federally mandated to be accurately calibrated, so regardless of what pressure etc or how you dispense it, that number
SHOULD be accurate.
It does not matter what that number is - whether you filled it when tank was 1/4 or half full (although the more you put in the more accurate the calculation will be) as long as you equate that specific fill to the volume consumed in Injector counts for that initial calibration.
You should only have to do that calibration once, although you can redo it if you find you are 'off' a little (perhaps tank was not completely filled before and after that initial calibration fill)
https://www.quora.com/How-accurate-are-the-pumps-in-gas-stations
<0.3% is the allowable accuracy error
If you are seeing different volumes of your fill, it is fairly likely that indeed your real fill volume is different each time. It is almost impossible to compare fill to fill volume unless your tank starts at completely empty and is filled to completely full; anything between is just an approximate guess on the users part. *
... So given that reality, how does FUELBOT operation make things better ?
The Fuelbot will give you an extremely accurate indication once it is initially programmed by knowing how much fuel was CONSUMED (that is the critical term here) against how much it took to fill it to the same point as the previous reference
(that is why you are instructed to fill to the neck, so the reference point is the same). Once programmed the consumption rate will be actually calculated to show whatever you have remaining to the 'spec' capacity that you entered initially.
The number you enter for the tank capacity, has no actual bearing on the fuel rate CONSUMPTION itself, only the predictor to what point it is 'empty'
If you want to be able to live all the way to the fumes, then you get the absolute capacity of the tank.
But you can build in your own 'cushion' by setting a slightly lower 'spec' tank volume.
So let's say that the tank really takes an actual 24L from completely empty to completely full;
If you enter 24 as the volume, then yes, if you got the calibration correct, you would hit that '0' level pretty predictably every time.
An alternative is to be slightly conservative - say 23L (it does not use this number in any way to calculate how much fuel the bike is using - only what the empty point is)
Now the firmware simply thinks there is a 23L tank, so it will now always predict to the zero mark at 1L remaining; so you have a built-in reserve if you will.
The consumption rate is going to be identical in the computation regardless of whether you put 23 or 24 as the tank volume - it simply will predict zero at whatever that reserve limit you built in.
Taken to extreme you could even enter 20L for example and when your FuelBot says 'zero' you would always have 4L (or 1gal) left
But you really don't need to build in a big reserve - the only thing you really want avoid is using a BIGGER number than the tank actually holds!
i.e if you say the tank hold 25L, you will run out of fuel before the FuelBot says zero!!
*footnote - once you have calibrated it correctly, you WILL be able to compare the volume of your fill between one pump and another against what you have used as indicated by FuelBot.
